Chemokines, chemokine receptors, and cancer metastasis

CCR7-expressing B16 melanoma cells downregulate interferon-γ-mediated inflammation and increase lymphangiogenesis in the tumor microenvironment

The expression of the CC chemokine receptor-7 (CCR7) by cancers, including melanoma, augments lymph node (LN) metastasis, but little is known about its role in lymphangiogenesis and anti-tumor immunity. We injected control B16 murine melanoma cells (pLNCX2-B16) and CCR7-overexpressing B16 cells (CCR7-B16) in murine footpads and compared resulting tumors at the protein and mRNA level using immunostaining, Affymetrix gene microarray and quantitative reverse-transcriptase PCR. Although control and CCR7-B16 primary tumors were of similar size, LN metastasis was dramatically enhanced in CCR7-B16 tumors. Microarray analysis of leukocyte-depleted pLNCX2-B16 and CCR7-B16 tumor cell suspensions showed that three major groups of genes linked to interferon (IFN)-γ signaling pathways (for example, STAT1, CXCR 9-11, CCL5 and CXCL10, major histocompatibility complex (MHC) I and MHC II) were downregulated in the CCR7-B16 tumor microenvironment, suggesting activation through CCR7 can downregulate pathways critical for host anti-tumor immunity. In addition, mRNA expression of the lymphatic marker podoplanin was upregulated in CCR7-B16 tumors by 3.35-fold versus control tumors. Anti-podoplanin monoclonal antibody staining revealed a three-fold increase in intratumoral CCL21-expressing lymphatic vessels, as well as a two-fold increase in the number of invading tumor cells per lymphatic vessel in CCR7-B16 versus control tumors. Enhanced anti-vascular endothelial growth factor C (VEGF-C) staining was present in CCR7-B16 versus control tumors, suggesting that VEGF-C may have a role in the CCR7-mediated lymphangiogenesis. In summary, CCR7-B16 tumors show a striking decrease in IFN-γ-mediated inflammatory gene expression in contrast to increased expression of VEGF-C, CCL21 and podoplanin by lymphatic vessels. Enhanced lymphangiogenesis may contribute to the dramatic increase in LN metastasis that is observed in the CCR7-expressing tumors.

Upregulation of C-X-C chemokine receptor type 1 expression is associated with late-stage gastric adenocarcinoma

Chemokine receptors play multiple roles in the development and progression of various tumor types. The aim of this study was to examine C-X-C chemokine receptor type 1 (CXCR1) protein expression in gastric adenocarcinoma and to investigate the clinical implications of CXCR1 upregulation. Expression of CXCR1 protein in 83 specimens of sporadic gastric adenocarcinoma and their corresponding non-neoplastic mucosa obtained by gastrectomy was assayed using immunohistochemistry. The intensity of immunostaining in tumor tissue was considered strong when tumor tissue staining was more intense than in the corresponding non-neoplastic mucosa; the intensity was null when staining was weaker in the tumor than in the corresponding non-neoplastic mucosa; and the intensity was weak when staining was similar in both tissues. Microvascular density in tumor tissue and its corresponding non-neoplastic mucosa was measured using monoclonal antibody against CD34. A strong correlation was observed between elevated CXCR1 protein expression and tumor stage (P<0.05). T stage, N stage and overall stage positively correlated with CXCR1 protein expression. Microvascular density was higher in tumors with strong CXCR1 protein expression, but the correlation with CXCR1 was not linear (P=0.07). Multiple logistic regression analyses showed that, compared to no or weak expression, overexpression of CXCR1 protein was a significant risk factor for high N stage (N2, N3). These results indicate that CXCR1 may be considered as a new and promising target for gastric adenocarcinoma therapy.

Engineering lymph node homing of ex vivo-expanded human natural killer cells via trogocytosis of the chemokine receptor CCR7

Natural killer (NK) cells have gained significant attention in adoptive immunotherapy for cancer. Consequently, novel methods of clinical-grade expansion of NK cells have emerged. Subsets of NK cells express a variety of chemokine receptors. However, to expand the scope of adoptively transferred NK cell homing to various malignancies, expression of corresponding chemokine receptors on NK cells is essential. Here, we have explored the use of trogocytosis as a tool to transiently express the chemokine receptor CCR7 on expanded human NK cells with the aim to enhance their homing to lymph nodes. We generated a K562-based "donor" cell line expressing CCR7, Clone9.CCR7, to transfer CCR7 onto NK cells via trogocytosis. CCR7 expression occurred in 80% of expanded NK cells within 1 hour after coculture with Clone9.CCR7. After removal of the donor cells from the coculture, the CCR7 expression on NK cells steadily declined to baseline levels by 72 hours. The acquired CCR7 receptors mediated in vitro migration of NK cells toward CCL19 and CCL21 and increased the lymph node homing by 144% in athymic nude mice. This is the first report on exploiting trogocytosis to rapidly and transiently modify lymphocytes, without direct genetic intervention, for adoptive transfer.

CCL5, CCR1 and CCR5 in murine glioblastoma: immune cell infiltration and survival rates are not dependent on individual expression of either CCR1 or CCR5

Glioblastoma multiforme (GBM) is the most malignant brain tumor. Microglia/macrophages are found within human GBM where they likely promote tumor progression. We report that CCL5, CCR1, and CCR5 are expressed in glioblastoma. Individual deletion of CCR1 or CCR5 had little to no effect on survival of tumor bearing mice, or numbers of glioblastoma-infiltrated microglia/macrophages or lymphocytes. CCL5 promoted in vitro migration of wild type, CCR1- or CCR5-deficient microglia/macrophages that was blocked by the dual CCR1/CCR5 antagonist, Met-CCL5. These data suggest that CCL5 functions within the glioblastoma microenvironment through CCR1 and CCR5 in a redundant manner.

High expression of CXCR4 and CXCR7 predicts poor survival in gallbladder cancer

Chemokine receptors play a prominent role in cancer progression and metastasis. This study investigated whether the expression of CXC chemokine receptor types 4 and 7 (CXCR4 and CXCR7, respectively), determined immunohistochemically, was associated with clinicopathological characteristics and postoperative survival in gallbladder cancer specimens from 72 patients. CXCR4 was detected in the cytoplasm and/or nucleus of gallbladder cancer cells, but CXCR7 was detected only in the cytoplasm. Expression of either CXCR7 or CXCR4 in the cytoplasm was associated with tumour stage. Expression of nuclear CXCR4 was associated with lymph node metastases and lymphatic invasion. Cytoplasmic expression of CXCR4 and CXCR7 were each independent risk factors for worse postoperative survival. Further research is required to clarify the mechanisms involved in these associations and to determine their potential prognostic and therapeutic implications.

The role of immunoglobulin superfamily cell adhesion molecules in cancer metastasis

Metastasis is a major clinical problem and results in a poor prognosis for most cancers. The metastatic pathway describes the process by which cancer cells give rise to a metastatic lesion in a new tissue or organ. It consists of interconnecting steps all of which must be successfully completed to result in a metastasis. Cell-cell adhesion is a key aspect of many of these steps. Adhesion molecules belonging to the immunoglobulin superfamily (Ig-SF) commonly play a central role in cell-cell adhesion, and a number of these molecules have been associated with cancer progression and a metastatic phenotype. Surprisingly, the contribution of Ig-SF members to metastasis has not received the attention afforded other cell adhesion molecules (CAMs) such as the integrins. Here we examine the steps in the metastatic pathway focusing on how the Ig-SF members, melanoma cell adhesion molecule (MCAM), L1CAM, neural CAM (NCAM), leukocyte CAM (ALCAM), intercellular CAM-1 (ICAM-1) and platelet endothelial CAM-1 (PECAM-1) could play a role. Although much remains to be understood, this review aims to raise the profile of Ig-SF members in metastasis formation and prompt further research that could lead to useful clinical outcomes.

Antibody Microarray Analysis of Signaling Networks Regulated by Cxcl13 and Cxcr5 in Prostate Cancer

Advanced prostate cancer (PCa) often spreads to distant organs, leading to increased morbidity and mortality. It is now well established that chemokines and their cognate receptors play a crucial role in the multi-step process of metastasis. We have previously identified CXCR5 to be highly expressed by PCa tissues and cell lines and its specific ligand, CXCL13, is significantly elevated in the serum of patients with PCa and differentiated PCa cases with other benign prostatic diseases. CXCR5:CXCL13 interactions promote PCa cell invasion, migration, and differential matrix metalloproteinase (MMP) expression. Thus, it is important to understand the molecular and cellular processes that mediate these events. In this study, we quantified changes in apoptosis, cell cycle, and cytoskeleton rearrangement biological pathways from CXCL13-treated hormone refractory PCa cell line (PC3) to better elucidate the signaling pathways activated by CXCL13:CXCR5 interaction. Using antibody arrays that displayed 343 different protein- and phosphorylation-specific antibodies, regulatory networks that control cancer progression signaling cascades were identified. Three regulatory networks were dramatically induced by CXCL13: Akt1/2-cyclin-dependent kinases (Cdk1/2)-Cdk inhibitor 1B (CDKN1B), Integrinβ3-focal adhesion kinase (Fak)/Src-Paxillin(PXN), and Akt-Jun-cAMP response-element binding protein (CREB1). In general, phosphoinositide-3 kinase (PI3K)/Akt and stress-activated protein kinase (SAPK)/c-jun kinase (JNK) were the major signaling pathways modulated by CXCL13 in PCa cells. This cluster analysis revealed proteins whose activation patterns can be attributed to CXCL13:CXCR5 interaction in the androgen-independent PC3 cell line. Taken together, these results suggest that CXCL13 contributes to cell-signaling cascades that regulate advanced PCa cell invasion, growth, and/or survival.

Norepinephrine promotes the β1-integrin-mediated adhesion of MDA-MB-231 cells to vascular endothelium by the induction of a GROα release

The migratory activity of tumor cells and their ability to extravasate from the blood stream through the vascular endothelium are important steps within the metastasis cascade. We have shown previously that norepinephrine is a potent inducer of the migration of MDA-MB-468 human breast carcinoma cells and therefore investigated herein, whether the interaction of these cells as well as MDA-MB-231 and MDA-MB-435S human breast carcinoma cells with the vascular endothelium is affected by this neurotransmitter as well. By means of a flow-through assay under physiologic flow conditions, we show that norepinephrine induces an increase of the adhesion of the MDA-MB-231 cells, but not of MDA-MB-468 and MDA-MB-435S cells to human pulmonary microvascular endothelial cells (HMVEC). The adhesion of MDA-MB-231 cells was based on a norepinephrine-mediated release of GROα from HMVECs. GROα caused a β1-integrin-mediated increase of the adhesion of MDA-MB-231 cells. Most interestingly, this effect of norepinephrine, similar to the aforementioned induction of migration in MDA-MB-468 cells, was mediated by β-adrenergic receptors and therefore abrogated by β-blockers. In conclusion, norepinephrine has cell line-specific effects with regard to certain steps of the metastasis cascade, which are conjointly inhibited by clinically established β-blockers. Therefore, these results may deliver a molecular explanation for our recently published retrospective data analysis of patients with breast cancer which shows that β-blockers significantly reduce the development of metastases.

The chemokine system and cancer

Chemokines (chemo-attractant cytokines) are a group of small proteins that act together with their cell surface receptors, in development, normal physiology and immune responses, to direct cells to specific locations throughout the body. Cancer cells acquire the ability to subvert the chemokine system, such that these molecules and their receptors become important regulators of cell movement into and out of the tumour microenvironment and major players in cancer biology.

CXCR4/CXCL12 expression profile is associated with tumor microenvironment and clinical outcome of liver metastases of colorectal cancer

Interaction between CXCR4 and CXCL12 plays a role in tumor progression. The present study examined CXCR4, CXCL12 and CD133 expression in liver metastases of colorectal cancer (CLM) and determined whether the expression profiles affect the tumor microenvironment and thus progression, and whether they could serve as a prognostic marker for survival. Liver metastases of colorectal cancer collected from 92 patients were evaluated by CXCR4, CXCL12 and CD133 immunohistochemistry and clinicopathological data were analyzed. The expression profile of CXCR4 was determined in the colorectal cancer cell line, SW48. The expression of cytoplasmic CXCR4 was higher in 36 (39%) patients than that indicated by CXCR4 staining intensity of hepatocytes. High levels of nuclear CXCR4 expression in 23 (25%) patients significantly correlated with CXCL12 expression in hepatocytes. Nuclear CXCR4 expression was increased in the cancer cells after exposure to CXCL12. Univariate and multivariate analyses demonstrated that the high levels of nuclear CXCR4 and CXCL12 expression in hepatocytes were significantly better prognostic factors for overall and hepatic disease-free survival in patients with CLM. The expression of CXCR4 and CXCL12 in CLM may have an interactive effect that could alter the tumor microenvironment. CXCR4 expression in metastatic liver tumors together with the upregulation of CXCL12 in hepatocytes may help to predict the clinical outcomes of patients with CLM after hepatectomy.

The use of chemokine-releasing tissue engineering scaffolds in a model of inflammatory response-mediated melanoma cancer metastasis

Inflammatory responses and associated products have been implicated in cancer metastasis. However, the relationship between these two processes is uncertain due to the lack of a suitable model. Taking advantage of localized and controllable inflammatory responses induced by biomaterial implantation and the capability of tissue scaffolds to release a wide variety of chemokines, we report a novel system for studying the molecular mechanisms of inflammation-mediated cancer metastasis. The animal model is comprised of an initial subcutaneous implantation of biomaterial microspheres which prompt localized inflammatory responses, followed by the transplantation of metastatic cancer cells into the peritoneal cavity or blood circulation. Histological results demonstrated that substantial numbers of B16F10 cells were recruited to the site nearby biomaterial implants. There was a strong correlation between the degree of biomaterial-mediated inflammatory responses and number of recruited cancer cells. Inflammation-mediated cancer cell migration was inhibited by small molecule inhibitors of CXCR4 but not by neutralizing antibody against CCL21. Using chemokine-releasing scaffolds, further studies were carried out to explore the possibility of enhancing cancer cell recruitment. Interestingly, erythropoietin (EPO) releasing scaffolds, but not stromal cell-derived factor-1α-releasing scaffolds, were found to accumulate substantially more melanoma cells than controls. Rather unexpectedly, perhaps by indirectly reducing circulating cancer cells, mice implanted with EPO-releasing scaffolds had ~30% longer life span than other groups. These results suggest that chemokine-releasing scaffolds may potentially function as implantable cancer traps and serve as powerful tools for studying cancer distraction and even selective annihilation of circulating metastatic cancer cells.

Down-regulation of CXCR7 inhibits the growth and lung metastasis of human hepatocellular carcinoma cells with highly metastatic potential

CXCR7, a recently identified chemokine receptor, has been implicated in directing cancer metastasis. In the present study, the potential roles of CXCR7 in the growth and metastasis of hepatocellular carcinoma (HCC) were evaluated. A chemokine receptor gene chip was used to compare the expression of CXCR7 in HCC cell lines with different metastatic potential. Effects of targeting CXCR7 by RNA interference (RNAi) on the proliferation and metastasis of HCCLM3 cells were observed in vitro and in vivo. CXCR7 expression in 116 specimens from patients with or without metastatic HCC was assessed by tissue microarray. As a result, the gene chip showed that expression of CXCR7 was significantly higher in the highly metastatic HCCLM3 cells, which was confirmed by real-time RT-PCR and Western blotting. Chemotaxis assays showed that HCCLM3 cells responded to SDF-1α from 1 to 100 μg/l and lung extractions (1 g/l). Furthermore, down-regulation of CXCR7 in HCCLM3 cells by RNAi inhibited the proliferation and invasion of tumor cells in vitro. Moreover, CXCR7 knockdown significantly reduced the activity of matrix metalloproteinase-2 and matrix metalloproteinase-9. RNAi of CXCR7 in the HCCLM3 cells also decreased the growth of tumors and the number of lung metastases in nude mice. The tissue microarray showed that HCCs with high expression of CXCR7 were prone to metastasize to the lung. These findings suggest that CXCR7 plays critical roles in the growth and metastasis of HCC. RNAi of CXCR7 inhibits the growth and invasion of tumor cells, which indicates that CXCR7 may be a potential molecular target for use in HCC therapy.

Plumbagin inhibits invasion and migration of breast and gastric cancer cells by downregulating the expression of chemokine receptor CXCR4

Background

Increasing evidence indicates that the interaction between the CXC chemokine receptor-4 (CXCR4) and its ligand CXCL12 is critical in the process of metastasis that accounts for more than 90% of cancer-related deaths. Thus, novel agents that can downregulate the CXCR4/CXCL12 axis have therapeutic potential in inhibiting cancer metastasis.

Methods

In this report, we investigated the potential of an agent, plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone), for its ability to modulate CXCR4 expression and function in various tumor cells using Western blot analysis, DNA binding assay, transient transfection, real time PCR analysis, chromatin immunoprecipitation, and cellular migration and invasion assays.

Results

We found that plumbagin downregulated the expression of CXCR4 in breast cancer cells irrespective of their HER2 status. The decrease in CXCR4 expression induced by plumbagin was not cell type-specific as the inhibition also occurred in gastric, lung, renal, oral, and hepatocellular tumor cell lines. Neither proteasome inhibition nor lysosomal stabilization had any effect on plumbagin-induced decrease in CXCR4 expression. Detailed study of the underlying molecular mechanism(s) revealed that the regulation of the downregulation of CXCR4 was at the transcriptional level, as indicated by downregulation of mRNA expression, inhibition of NF-κB activation, and suppression of chromatin immunoprecipitation activity. In addition, using a virtual, predictive, functional proteomics-based tumor pathway platform, we tested the hypothesis that NF-κB inhibition by plumbagin causes the decrease in CXCR4 and other metastatic genes. Suppression of CXCR4 expression by plumbagin was found to correlate with the inhibition of CXCL12-induced migration and invasion of both breast and gastric cancer cells.

Conclusions

Overall, our results indicate, for the first time, that plumbagin is a novel blocker of CXCR4 expression and thus has the potential to suppress metastasis of cancer.

Thymoquinone inhibits the CXCL12-induced chemotaxis of multiple myeloma cells and increases their susceptibility to Fas-mediated apoptosis

In multiple myeloma (MM), malignant plasma cells reside in the bone marrow, where they accumulate in close contact with stromal cells. The mechanisms responsible for the chemotaxis of malignant plasma cells are still poorly understood. Thus, we investigated the mechanisms involved in the chemotaxis of MDN and XG2 MM cell lines. Both cell lines strongly expressed CCR9, CXCR3 and CXCR4 chemokine receptors but only migrated toward CXCL12. Activation of CXCR4 by CXCL12 resulted in the association of CXCR4 with CD45 and activation of PLCβ3, AKT, RhoA, IκBα and ERK1/2. Using siRNA-silencing techniques, we showed CD45/CXCR4 association is essential for CXCL12-induced migration of MM cells. Thymoquinone (TQ), the major active component of the medicinal herb Nigella sativa Linn, has been described as a chemopreventive and chemotherapeutic compound. TQ treatment strongly inhibited CXCL12-mediated chemotaxis in MM cell lines as well as primary cells isolated from MM patients, but not normal PBMCs. Moreover, TQ significantly down-regulated CXCR4 expression and CXCL12-mediated CXCR4/CD45 association in MM cells. Finally, TQ also induced the relocalization of cytoplasmic Fas/CD95 to the membrane of MM cells and increased CD95-mediated apoptosis by 80%. In conclusion, we demonstrate the potent anti-myeloma activity of TQ, providing a rationale for further clinical evaluation.

The role of CXCR2 chemokine receptors in the oral squamous cell carcinoma

This study evaluated the relevance of CXCR2 chemokine receptors in oral squamous cell carcinoma, by means of in vitro and in vivo approaches. The in vitro incubation of the selective and non-peptide CXCR2 receptor antagonist N-(2-hydroxy-4-nitrophenyl)-N9-(2-bromophenyl) Urea (SB225002; 25 to 800 nM) produced a time- and concentration-dependent inhibition of SCC158 (rat) and HN30 (human) cell lines viability. Conversely, this antagonist did not significantly affect the viability of the immortalized keratinocyte lineage, HaCaT. Additionally, the incubation of human IL-8 and rat CINC-1 CXCR2 agonists produced a concentration-related increase on HN30 and SCC158 proliferation. The submucosal injection of SCC158 cells (5 × 10(6) cells) into the tongue of Fischer 344 rats induced tumor development, which displayed typical clinical features. Immunohistochemical analysis of rat tongue biopsies revealed a marked increase of CXCR2 receptor immunoreactivity, which was accompanied by augumented expression of VEGF and caspase-3. Our data suggests an important role for CXCR2 receptors in oral squamous cell carcinoma.

CXCL13 mediates prostate cancer cell proliferation through JNK signalling and invasion through ERK activation

OBJECTIVES

  The focus of this study was to determine the dedicator of cytokinesis 2 (DOCK2), extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase-1 (JNK) and Akt signals involved in CXCL13-mediated prostate cancer (PCa) cell invasion and proliferation.

MATERIALS AND METHODS

  Androgen-sensitive (LNCaP), hormone-refractory (PC3) cells and normal cells (RWPE-1) were used to determine CXCL13-mediated PCa cell invasion and proliferation. Immuno-blotting, fast activated cell-based (FACE) ELISA, caspase activity, cell invasion and proliferation assays were performed to ascertain some of the signalling events involved in PCa cell proliferation and invasion.

RESULTS

  Unlike androgen-sensitive LNCaP cells, we report for the first time that the hormone-refractory cell line, PC3, expresses DOCK2. CXCL13-mediated LNCaP and PC3 cell invasion was regulated by Akt and ERK1/2 activation in a DOCK2-independent fashion. CXCL13 also promoted LNCaP cell proliferation in a JNK-dependent fashion even in the absence of DOCK2. In contrast, CXCL13 induced PC3 cell proliferation through JNK activation, which required DOCK2.

CONCLUSIONS

  Our results show CXCL13-mediated PCa cell invasion requires Akt and ERK1/2 activation and suggests a new role for DOCK2 in proliferation of hormone-refractory CXCR5-positive PCa cells.

Chemokines: key players in cancer progression and metastasis

Instructed cell migration is a fundamental component of various biological systems and is critical to the pathogenesis of many diseases including cancer. Role of chemokines in providing navigational cues to migrating cancer cells bearing specific receptors is well established. However, functional mechanisms of chemokine are not well implicit, which is crucial for designing new therapeutics to control tumor growth and metastasis. Multiple functions and mode of actions have been advocated for chemokines and their receptors in the progression of primary and secondary tumors. In this review, we have discussed current advances in understanding the role of the chemokines and their corresponding receptor in tumor progression and metastasis.

Expression of the inflammatory chemokines CCL2, CCL5 and CXCL2 and the receptors CCR1-3 and CXCR2 in T lymphocytes from mammary tumor-bearing mice

Chemokines and their receptors have been studied in several solid tumor models as mediators of inflammation. In turn, inflammation has been implicated in the promotion and progression of tumors, and as such, chemokines have been proposed as novel molecular targets for chemotherapy. While the expression of these molecules has been described in tumor cells, endothelial cells, macrophages and neutrophils, less attention has been paid to the expression profile of these molecules by T lymphocytes in the periphery or infiltrating the tumor. Using the D1-DMBA-3 murine mammary adenocarcinoma model, we aimed to better characterize the differential expression of chemokines and/or their receptors in the host and in the tumor microenvironment, and specifically, in the T cells of tumor-bearing mice compared to normal control animals. We found that T lymphocytes from tumor-bearing mice express the pro-inflammatory chemokines, CCL2, CCL5 and CXCL2, as well as the chemokine receptors, CCR1, CCR2, CCR3 and CXCR2.

Inflammation and tumor microenvironment in lymph node metastasis

In nearly all human cancers, the presence of lymph node (LN) metastasis increases clinical staging and portends worse prognosis (compared to patients without LN metastasis). Herein, principally reviewing experimental and clinical data related to malignant melanoma, we discuss diverse factors that are mechanistically involved in LN metastasis. We highlight recent data that link tumor microenvironment, including inflammation (at the cellular and cytokine levels) and tumor-induced lymphangiogenesis, with nodal metastasis. Many of the newly identified genes that appear to influence LN metastasis facilitate general motility, chemotactic, or invasive properties that also increase the ability of cancer cells to disseminate and survive at distant organ sites. These new biomarkers will help predict clinical outcome and point to novel future therapies in metastatic melanoma as well as other cancers.

Recently identified biomarkers that promote lymph node metastasis in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous cancer that arises in the upper aerodigestive tract. Despite advances in knowledge and treatment of this disease, the five-year survival rate after diagnosis of advanced (stage 3 and 4) HNSCC remains approximately 50%. One reason for the large degree of mortality associated with late stage HNSCC is the intrinsic ability of tumor cells to undergo locoregional invasion. Lymph nodes in the cervical region are the primary sites of metastasis for HNSCC, occurring before the formation of distant metastases. The presence of lymph node metastases is strongly associated with poor patient outcome, resulting in increased consideration being given to the development and implementation of anti-invasive strategies. In this review, we focus on select proteins that have been recently identified as promoters of lymph node metastasis in HNSCC. The discussed proteins are involved in a wide range of critical cellular functions, and offer a more comprehensive understanding of the factors involved in HNSCC metastasis while additionally providing increased options for consideration in the design of future therapeutic intervention strategies.

Effect of Oxymatrine Combined with Low Dose 5-FU on Lymphatic Vessel and Microvascular Endothelial Cell Growth of Gastric Cancer in a Severe Combined Immunodeficient Mouse Orthotopic Implantation Model

In this study, we explored the effect of Oxymatrine combined with low dose 5-Fu on lymphatic vessel and vascular endothelial growth factor of orthotopic implantated gastric cancer in severe combined immunodeficient (SCID) nude mice. Human gastric cancer cell line SGC-7901 was orthotopically implanted into the gastric tract of nude mice. Nude mice were treated with normal saline (control group), low dose 5-Fu, oxymatrine, oxymatrine combined with low dose 5-Fu using intraperitoneal injection. The expression of LVD, VEGF-C, VEGF-D, VEGF-R-3 and their Ct were analyzed in a severe combined immunodeficient mouse orthotopic implantatation gastric cancer model. We found that oxymatrine combined with low dose 5-Fu could decrease LVD and inhibit VEGF expression by a synergistic effect in SCID nude mouse orthotopic implantatation gastric cancer model.

CXCL9 induces chemotaxis, chemorepulsion and endothelial barrier disruption through CXCR3-mediated activation of melanoma cells

Background:

Metastasis is associated with poor prognosis for melanoma. The formation of metastases is a multi-step process, in which cancer cells can subsequently acquire the potential to intravasate into the blood or lymph vessels, disseminate through the circulation, extravasate through the endothelium and invade the connective tissue. There is increasing evidence that chemokines have a pivotal role in the dissemination and establishment of melanoma metastasis.

Methods:

We isolated melanoma cells from melanoma metastasis and performed different migration assays and transendothelial resistance measurements of endothelial monolayers co-cultured with melanoma cells, in order to monitor barrier function and diapedesis and confirmed these results by confocal microscopy.

Results:

We observed that tumour endothelial cells (ECs) secrete high levels of CXCL9 in all, and CXCL10 in most melanoma metastases. Migration studies revealed that low concentrations of these chemokines induce chemotaxis, whereas high concentrations induce spontaneous migration of melanoma cells (chemokinesis/chemorepulsion) and the disruption of the endothelial barrier, resulting in an accelerated transendothelial migration (TEM). Addition of anti-CXCL9 or anti-CXCR3 antibodies to the co-cultures delayed the TEM of melanoma cells.

Conclusion:

Our data represent novel mechanisms by which tumour cells in melanoma metastases might use the chemokine-expressing endothelium to leave the tumour and eventually to form additional metastases at distinct sites.

CCR10 and CCL27 are overexpressed in cutaneous squamous cell carcinoma

C-C chemokine receptor (CCR)10 is a specific receptor for chemokine ligand (CCL)27, a selective chemoattractant for skin-associated memory T cells to cutaneous sites. In melanoma, CCR10 increases the ability of neoplastic cells to grow, invade tissues, disseminate to lymph nodes, and escape the host immune responses. In this study, we investigated the expression of CCR10 and its ligand CCL27 in squamous cell carcinoma (SCC). CCR10 and CCL27 were expressed in SCC, actinic keratosis (AK), Bowen's disease, and seborrheic keratosis (predominantly prickle cell type), but not in seborrheic keratosis (predominantly basal cell type) and basal cell carcinoma. Furthermore, CCR10 and CCL27 were overexpressed in SCC relative to Bowen's disease, an early stage of SCC. Consistently, a human SCC cell line, A253 cells, and HaCaT cells exhibited CCL27 production that was strongly induced by tumor necrosis factor-α and interleukin-1β. Finally, A253 cells expressed stronger intracellular CCR10 compared to HaCaT cells by flow cytometry. These results suggest that CCR10 and CCL27 overexpression in SCC is related to the progression of SCC and is useful for the diagnosis of SCC.

Roles of inflammatory cytokines in the progression of gastric cancer: friends or foes?

Increasing evidence is being reported regarding the hypothesis that several proinflammatory and anti-inflammatory cytokines may promote tumor progression and affect the host antitumor response. However, the manner in which a local cytokine network operates in tumor development remains unclear. We reviewed the literature to examine the consequences of novel insights into inflammatory cytokines associated with gastric cancer progression. The Medline and EMBASE databases were searched for publications regarding the role of inflammatory cytokines in the development of gastric cancer. A number of studies have suggested that several proinflammatory and anti-inflammatory cytokines promote tumor progression through the direct activation of nuclear factor-κB (NF-κB) and the upregulation of angiogenesis and adhesion molecules. Furthermore, these processes suppress host antitumor immunity, leading to tumor progression and metastasis. In patients with advanced gastric cancer, most cytokines that enhance or suppress host antitumor immunity appear to have elevated serum and local expression levels. The net cytokine environment fluctuates at various stages of tumor development. In conclusion, a more detailed understanding of the differential roles of malignant cell-derived and hostderived cytokines at different stages of the malignant process could, consequently, open new avenues for the manipulation of cytokine expression and function in cancer immunotherapy for gastric cancer.

Roles of inflammatory cytokines in the progression of gastric cancer: friends or foes?

Increasing evidence is being reported regarding the hypothesis that several proinflammatory and anti-inflammatory cytokines may promote tumor progression and affect the host antitumor response. However, the manner in which a local cytokine network operates in tumor development remains unclear. We reviewed the literature to examine the consequences of novel insights into inflammatory cytokines associated with gastric cancer progression. The Medline and EMBASE databases were searched for publications regarding the role of inflammatory cytokines in the development of gastric cancer. A number of studies have suggested that several proinflammatory and anti-inflammatory cytokines promote tumor progression through the direct activation of nuclear factor-κB (NF-κB) and the upregulation of angiogenesis and adhesion molecules. Furthermore, these processes suppress host antitumor immunity, leading to tumor progression and metastasis. In patients with advanced gastric cancer, most cytokines that enhance or suppress host antitumor immunity appear to have elevated serum and local expression levels. The net cytokine environment fluctuates at various stages of tumor development. In conclusion, a more detailed understanding of the differential roles of malignant cell-derived and hostderived cytokines at different stages of the malignant process could, consequently, open new avenues for the manipulation of cytokine expression and function in cancer immunotherapy for gastric cancer.

CXCL8 chemokines in teleost fish: two lineages with distinct expression profiles during early phases of inflammation

BACKGROUND

During the inflammatory process, chemokine CXCL8 plays a pivotal role in recruitment of human neutrophilic granulocytes. A diversity of sequences similar to CXCL8 was reported in fish, but their evolutionary relationships and functional homology with their human homolog remain unclear.

PRINCIPAL FINDINGS

We screened fish genomes to seek for sequences related to CXCL8. A first lineage was retrieved in all teleosts, while a second CXCL8 lineage was found in zebrafish and carp only. An early inflammatory function for both lineages was indicated by several lines of evidence. The induction of carp CXCL8s, CXCb, and CXC receptor-1 and -2 was analyzed after in vitro stimulation of leukocyte subpopulations and in two in vivo inflammation models. Recombinant proteins of carp CXCL8 proteins were produced and showed significant chemotactic activity for carp leukocytes.

CONCLUSIONS

While both carp CXCL8s appear to be functional homologs of mammalian CXCL8, their different induction requirements and kinetics evoke a gene-specific sub-functionalization.

Butein downregulates chemokine receptor CXCR4 expression and function through suppression of NF-κB activation in breast and pancreatic tumor cells

The CXC chemokine receptor-4 (CXCR4), a Gi protein-coupled receptor for the ligand CXCL12/stromal cell-derived factor-1α (SDF-1α), is known to be expressed in various tumors. This receptor mediates homing of tumor cells to specific organs that express the ligand CXCL12 for this receptor and plays an important role in tumor growth, invasion, metastasis, and angiogenesis. Thus, a priori, agents that can downregulate CXCR4/CXCL12 signaling cascade have potential against cancer metastasis. In this study, we report the identification of butein (3, 4, 2', 4'-tetrahydroxychalcone) as a novel regulator of CXCR4 expression and function. We found that butein downregulated the expression of CXCR4 in HER2-overexpressing breast cancer cells in a dose- and time-dependent manner. The decrease in CXCR4 expression induced by butein was not cell type-specific as the inhibition also occurred in pancreatic, prostate, multiple myeloma, head and neck, and hepatocellular cancer cell lines. When investigated for the molecular mechanism(s), it was found that the downregulation of CXCR4 was not due to proteolytic degradation but rather to transcriptional regulation as indicated by downregulation of mRNA expression, inhibition of NF-κB activation evident by both DNA binding, and reporter assays, and suppression of chromatin immunoprecipitation activity. Suppression of CXCR4 expression by butein correlated with the inhibition of CXCL12-induced migration and invasion of both breast and pancreatic cancer cells. Overall, our results demonstrate for the first time that butein is a novel inhibitor of CXCR4 expression and thus has a potential in suppressing metastasis of cancer.

Insights into the regulation of chemokine receptors by molecular signaling pathways: functional roles in neuropathic pain

Inflammation plays a central role in the manner that the nervous system responds to injury. These effects include vasodilatation, increased vascular permeability, plasma extravasation, cell migration, and pain. Extracellular signals associated with inflammation may also lead to increased levels of pro-nociceptive chemokines/receptors that directly contribute to persistent or chronic pain behavior. To date, research focused on improving the treatment of chronic pain has largely ignored the role of inflammation-associated transcription factors such as nuclear transcription factor in activated T cells (NFAT). Herein we discuss the idea that activation of this transcription factor may be responsible for the production of chemokines receptors in both neuronal and non-neuronal cells of the peripheral nervous system. Taken together, a better understanding of the transcription of these pro-nociceptive genes may lead to the development of novel analgesic targets.

CXCL7-Mediated Stimulation of Lymphangiogenic Factors VEGF-C, VEGF-D in Human Breast Cancer Cells

Increased expression of lymphangiogenesis factors VEGF-C/D and heparanase has been correlated with the invasion of cancer. Furthermore, chemokines may modify matrix to facilitate metastasis, and they are associated with VEGF-C and heparanase. The chemokine CXCL7 binds heparin and the G-protein-linked receptor CXCR2. We investigated the effect of CXCR2 blockade on the expression of VEGF-C/D, heparanase, and on invasion. CXCL7 siRNA and a specific antagonist of CXCR2 (SB225002) were used to treat CXCL7 stably transfected MCF10AT cells. Matrigel invasion assays were performed. VEGF-C/D expression and secretion were determined by real-time PCR and ELISA assay, and heparanase activity was quantified by ELISA. SB225002 blocked VEGF-C/D expression and secretion (P < .01). CXCL7 siRNA knockdown decreased heparanase (P < .01). Both SB225002 and CXCL7 siRNA reduced the Matrigel invasion (P < .01). The MAP kinase signaling pathway was not involved. The CXCL7/CXCR2 axis is important for cell invasion and the expression of VEGF-C/D and heparanase, all linked to invasion.

Constitutive expression of the alpha4 integrin correlates with tumorigenicity and lymph node metastasis of the B16 murine melanoma

The lymphatic system plays a critical role in melanoma metastasis, and yet, virtually no information exists regarding the cellular and molecular mechanisms that take place between melanoma cells and the lymphatic vasculature. Here, we generated B16-F1 melanoma cells that expressed high (B16alpha(4)+) and negligible (B16alpha(4)-) levels of alpha(4) integrin to determine how the expression of alpha(4) integrins affects tumor cell interactions with lymphatic endothelial cells in vitro and how it impacts lymphatic metastasis in vivo. We found a direct correlation between alpha(4) integrin expression on B16-F1 melanoma cells and their ability to form adhesive interactions with monolayers of lymphatic endothelial cells. Adhesion of B16-F1 melanoma cells to lymphatic endothelial cells was mediated by the melanoma cell alpha(4) integrin binding to its counterreceptor, vascular cell adhesion molecule 1 (VCAM-1), that was constitutively expressed on the lymphatic endothelial cells. VCAM-1 was also expressed on the tumor-associated lymphatic vessels of B16-F1 and B16alpha(4)+ tumors growing in the subcutaneous space of C57BL/6J mice. B16-F1 tumors metastasized to lymph nodes in 30% of mice, whereas B16alpha(4)+ tumors generated lymph node metastases in 80% of mice. B16-F1 melanoma cells that were deficient in alpha(4) integrins (B16alpha(4)-) were nontumorigenic. Collectively, these data show that the alpha(4) integrin expressed by melanoma cells contributes to tumorigenesis and may also facilitate metastasis to regional lymph nodes by promoting stable adhesion of melanoma cells to the lymphatic vasculature.

PI3Kp110-, Src-, FAK-dependent and DOCK2-independent migration and invasion of CXCL13-stimulated prostate cancer cells

Background

Most prostate cancer (PCa)-related deaths are due to metastasis, which is mediated in part by chemokine receptor and corresponding ligand interaction. We have previously shown that PCa tissue and cell lines express high levels of the chemokine receptor CXCR5, than compared to their normal counterparts, and interaction of CXCR5 with its specific ligand (CXCL13) promoted PCa cell invasion, migration, and differential matrix metalloproteinase (MMP) expression. This study dissects some of the molecular mechanisms following CXCL13-CXCR5 interaction that mediate PCa cell migration and invasion.

Results

Using Western blot analysis, kinase-specific cell-based ELISAs, and migration and invasion assays, we show that PCa cell lines differentially express phosphoinositide-3 kinase (PI3K) catalytic subunit isoforms and dedicator of cytokinesis 2 (DOCK2). Specifically, we show that PC3 and normal prostatic epithelial (RWPE-1), but not LNCaP cell lines expressed DOCK2, while RWPE, PC3, and LNCaP cell lines expressed PI3K-p110α and -p110β. Moreover, PC3 selectively expressed PI3K-p110γ, but LNCaP and RWPE cell lines expressed PI3Kp110δ. CXCL13 caused CXCR5-dependent activation of the PI3Kp85α in LNCaP cells, and p85α as well as -p101 in PC3 cells. CXCL13-CXCR5 interaction regulated LNCaP and PC3 cell migration and invasion through extracellular signal-regulated kinase 1/2 (ERK1/2) activation that was primarily dependent on the PI3Kp110 isoform(s), Src, and focal adhesion kinase (FAK), but not DOCK2.

Conclusions

While additional studies will be needed to determine the PI3K-independent (i.e., DOCK2-mediated) and -dependent events that dictate PCa cell responsiveness to CXCL13, these data provide evidence of the existence of cell type- and stimulus-specific signaling events that support migration and invasion of PCa cells.

Chemokine receptor CXCR7 regulates the invasion, angiogenesis and tumor growth of human hepatocellular carcinoma cells

Background

In spite of recent advances in diagnostic and therapeutic measures, the prognosis of hepatocellular carcinoma (HCC) patients remains poor. Therefore, it is crucial to understand what factors are involved in promoting development of HCC. Evidence is accumulating that members of the chemokine receptor family are viewed as promising therapeutic targets in the fight against cancer. More recent studies have revealed that chemokine receptor CXCR7 plays an important role in cancer development. However, little is known about the effect of CXCR7 on the process of HCC cell invasion and angiogenesis. The aim of this study is to investigate the expression of CXCR7 in hepatocellular carcinoma tissues and cell lines and to evaluate the role of CXCR7 in tumor growth, angiogenesis and invasion of HCC cells.

Methods

We constructed CXCR7 expressing shRNA, and CXCR7shRNA was subsequently stably transfected into human HCC cells. We evaluated the effect of CXCR7 inhibition on cell invasion, adhesion, VEGF secretion, tube formation and tumor growth. Immunohistochemistry was done to assess the expression of CXCR7 in human hepatocellular carcinoma tissues and CD31 in tumor of mice. We also evaluated the effect of VEGF stimulation on expression of CXCR7.

Results

CXCR7 was overexpressed in hepatocellular carcinoma tissues. We showed that high invasive potential HCC cell lines express high levels of CXCR7. In vitro, CXCL12 was found to induce invasion, adhesion, tube formation, and VEGF secretion in SMMC-7721 cells. These biological effects were inhibited by silencing of CXCR7 in SMMC-7721 cells. In addition, we also found that VEGF stimulation can up-regulate CXCR7 expression in SMMC-7721 cells and HUVECs. More importantly, enhanced expression of CXCR7 by VEGF was founctional. In vivo, tumor growth and angiogenesis were suppressed by knockdown of CXCR7 in SMMC-7721 cells. However, silencing of CXCR7 did not affect metastasis of tumor in vivo.

Conclusions

Increased CXCR7 expression was found in hepatocellular carcinoma tissues. Knockdown of CXCR7 expression by transfected with CXCR7shRNA significantly inhibits SMMC-7721 cells invasion, adhesion and angiogenesis. Finally, down-regulation of CXCR7 expression lead to a reduction of tumor growth in a xenograft model of HCC. This study provides new insights into the significance of CXCR7 in invasion and angiogenesis of HCC.

Chemokine CCL3 facilitates the migration of hepatoma cells by changing the concentration intracellular Ca

AIM

Recurrence and metastasis are the major factors associated with the poor prognosis of hepatocellular carcinoma (HCC). It was confirmed that multiple chemokines and their receptors are related to the progression and metastasis of HCC. The aim of this research was to conduct an investigation into whether macrophage inflammatory protein-1alpha/CCL3, and its receptor CCR1 play a role in HCC invasion and metastasis.

METHODS

We used reverse transcription polymerase chain reaction, immunocytochemistry and flow cytometry to detect CCR1 mRNA and protein expression in the four hepatoma cell lines HepG2, Hep3B, HLE and HLF; and we conducted a microscope cell migration experiment to observe the pseudopodia formation and mobility of the hepatoma cells. The concentration of intracellular calcium was measured by fluorescence microscopy.

RESULTS

CCR1 mRNA and protein were positively expressed in the four hepatoma cell lines HepG2, Hep3B, HLE and HLF. Following CCL3 stimulation, obvious pseudopodia formation of hepatoma cells was observed using a fluorescence microscope. The cell migration experiment showed that after incubation with CCL3, the number of Hep3B cells which passed through the polycarbonate microporous filter membranes increased to an obvious extent. After CCL3 incubation, the intracellular Ca(2+) level of the Hep3B cells increased to an obvious extent.

CONCLUSION

Chemokine CCL3 facilitates the migration of hepatoma by changing the concentration intracellular Ca(2+). The CCL3-CCR1 axis may play an important role in HCC invasion and metastasis. It may also be a potential target for HCC therapy or for prevention of the recurrence and metastasis of HCC.

Chemokine CXCL14/BRAK transgenic mice suppress growth of carcinoma cell transplants. [corrected]

We reported previously that the forced expression of the chemokine BRAK, also called CXCL14 in head and neck squamous cell carcinoma (HNSCC) cells decreased the rate of tumor formation and size of tumor xenografts compared with mock-vector treated cells in athymic nude mice or in severe combined immunodeficiency mice. This suppression occurred even though the growth rates of these cells were the same under in vitro culture conditions, suggesting that a high expression level of the gene in tumor cells is important for the suppression of tumor establishment in vivo. The aim of this study was to determine whether CXCL14/BRAK transgenic mice show resistance to tumor cell xenografts or not. CXCL14/BRAK cDNA was introduced into male C57BL/6 J pronuclei, and 10 founder transgenic mice (Tg) were obtained. Two lines of mice expressed over 10 times higher CXCL14/BRAK protein levels (14 and 11 ng/ml plasma, respectively) than normal blood level (0.9 ng/ml plasma), without apparent abnormality. The sizes of Lewis lung carcinoma and B16 melanoma cell xenografts in Tg mice were significantly smaller than those in control wild-type mice, indicating that CXCL14/BRAK, first found as a suppressor of tumor progression of HNSCC, also suppresses the progression of a carcinoma of other tissue origin. Immunohistochemical studies showed that invasion of blood vessels into tumors was suppressed in tumor xenografts of CXCL14/BRAK Tg mice. These results indicate that CXCL14/BRAK suppressed tumor cell xenografts by functioning paracrine or endocrine fashion and that CXCL14/BRAK is a very promising molecular target for tumor suppression without side effects.

Screening for novel constitutively active CXCR2 mutants and their cellular effects

Chemokines play an important role in inflammatory, developmental, and homeostatic processes. Deregulation of this system results in various diseases including tumorigenesis and cancer metastasis. Deregulation can occur when constitutively active mutant (CAM) chemokine receptors are locked in the "on" position. This can lead to cellular transformation/tumorigenesis. The CXC chemokine receptor 2 (CXCR2) is a G-protein-coupled receptor (GPCR) expressed on neutrophils, some monocytes, endothelial cells, and some epithelial cells. CXCR2 activation with CXC chemokines induces leukocyte migration, trafficking, leukocyte degranulation, cellular differentiation, and angiogenesis. Activation of CXCR2 can lead to cellular transformation. We hypothesized that CAM CXCR2s may play a role in cancer development. In order to identify CXCR2 CAMs, potential mutant CXCR2 receptors were screened using a modified Saccharomyces cerevisiae high-throughput system. S. cerevisiae has been used successfully to identify GPCR/G-protein interactions and autocrine selection for peptide agonists. The CXCR2 CAMs identified from this screen were characterized in mammalian cells. Their ability to transform cells in vitro was shown using foci formation, soft-agar growth, impedance measurement assays, and in vivo tumor growth following hind flank inoculation into mice. Signaling pathways contributing to cellular transformation were identified using luciferase reporter assays. Studying constitutively active GPCRs is an approach to "capturing" pluridimensional GPCRs in a "locked" activation state. In order to address the residues necessary for CXCR2 activation, we used S. cerevisiae for screening novel CAMs and characterized them using mammalian reporter assays.

Induction of copper/zinc-superoxide dismutase by CCL5/CCR5 activation causes tumour necrosis factor-alpha and reactive oxygen species production in macrophages

Using two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis, we found that copper/zinc superoxide dismutase (Cu/Zn-SOD, SOD-1) was induced in constructed CCR5 stably transfected HEK 293 cells, but not in mock cells, treated with CCL5. CCL5-induced SOD-1 expression was also confirmed in HEK 293-CCR5 cells and CCR5-positive granulocyte-macrophage colony-stimulating factor-induced human macrophages and murine macrophage RAW264.7 cells. CCL5 and CCR5 interaction induced SOD-1 expression mainly via MEK-ERK activation. In addition, we provided evidence that upregulation of SOD-1 by CCL5/CCR5 activation occurred in parallel with the increased release of tumour necrosis factor-alpha and nitric oxide and production of intracellular reactive oxygen species as well as enhanced nuclear factor-kappaB transcriptional activity in CCR5-positive RAW264.7 cells. Conversely, the MEK1/2 inhibitor PD98059 significantly inhibited SOD-1 expression with the decrease of these biological responses. More importantly, inhibition of SOD-1 activity by disulfiram also strongly inhibited the CCL5-induced biological effects. These data suggest that SOD-1 mediates CCR5 activation by CCL5 and that pharmacological modulation of SOD-1 may be beneficial to CCR5-associated diseases.

Tight control of MEK-ERK activation is essential in regulating proliferation, survival, and cytokine production of CD34+-derived neutrophil progenitors

A plethora of extracellular stimuli regulate growth, survival, and differentiation responses through activation of the MEK-ERK MAPK signaling module. Using CD34+ hematopoietic progenitor cells, we describe a novel role for the MEK-ERK signaling module in the regulation of proliferation, survival, and cytokine production during neutrophil differentiation. Addition of the specific MEK1/2 inhibitor U0126 resulted in decreased proliferation of neutrophil progenitors. Conversely, transient activation of a conditionally active MEK1 mutant resulted in the expansion of progenitor cells, which thereafter differentiated normally into mature neutrophils. In contrast, chronic MEK1 activation was found to induce cell death of CD34+ neutrophil progenitors. Microarray analysis of CD34+ progenitor cells showed that activation of MEK1 resulted in changes in expression of a variety of cell-cycle modulating genes. Furthermore, conditional activation of MEK1 resulted in a dramatic increase in the expression of mRNA transcripts encoding a large number of hematopoietic cytokines, chemokines, and growth factors. These findings identify a novel role for MEK-ERK signaling in regulating the balance between proliferation and apoptosis during neutrophil differentiation, and they suggest the need for tight control of MEK-ERK activation to prevent the development of bone marrow failure.

Higher expression of chemokine receptor CXCR7 is linked to early and metastatic recurrence in pathological stage I nonsmall cell lung cancer

BACKGROUND

The authors elucidated particular chemokine receptors that are expressed on lung cancer cells, as well as the clinical significance of the expression of these chemokine receptors in completely resected nonsmall cell lung cancer (NSCLC).

METHODS

The authors examined gene expression of chemokine receptors (CCR1-11, CXCR1-7, XCR1, and CX3CR1) in 11 cell lines of lung cancer, and gene expression of CXCR3, CXCR4, and CXCR7 (CXCR3/4/7) in surgical specimens of 127 patients who underwent complete resection for their NSCLC between May 2001 and December 2002, using quantitative real-time reverse transcriptase-polymerase chain reaction (PCR). Mutation detection analysis of the EGFR genes using the PCR single-strand conformational polymorphism method was evaluated in patients with pathological (p-) stage I adenocarcinoma.

RESULTS

Substantial expression of CXCR3/4/7 mRNA was observed in all NSCLC cell lines examined. In p-stage I NSCLC, CXCR4 and CXCR7 expression values in patients with postoperative metastatic recurrence (Rec-Distant) were significantly higher than in those without recurrences (P = .003 and P = .007, respectively). In addition, the 5-year disease-free survival (DFS) rate of high CXCR7-expressing patients (63.2%) was significantly lower than that of low CXCR7-expressing patients (84.8%) (P = .033). The EGFR mutation was significantly more frequent in patients with higher CXCR7 expression (14 of 21 patients) than in those with lower CXCR7 expression (12 of 32 patients) (P = .038). A multivariate analysis confirmed that high CXCR7 expression was an independent and significant factor predicting a poor DFS in p-stage I NSCLC patients (P = .041).

CONCLUSIONS

Higher expression of CXCR7 is associated with Rec-Distant and poor DFS in patients with p-stage I NSCLC.

CXCR4 expression on circulating pan-cytokeratin positive cells is associated with survival in patients with advanced non-small cell lung cancer

BACKGROUND

The CXC chemokine, CXCL12, and its receptor, CXCR4 promote metastases of a variety of solid tumors, including non-small cell lung cancer (NSCLC). The expression of CXCR4 on tumor cells may represent a critical biomarker for their propensity to metastasize. This study was performed to evaluate the hypothesis that co-expression of pan-cytokeratin and CXCR4 may be a prognostic marker for patients with advanced NSCLC.

METHODS

We evaluated CXCR4 levels on circulating pan-cytokeratin positive cells from patients with NSCLC. NSCLC tumor and metastases were also assessed for the presence of CXCR4.

RESULTS

Pan-cytokeratin positive cells were increased in the circulation of patients with NSCLC, as compared to normal control subjects. Patients with pan-cytokeratin +/CXCR4+ = 2,500 cells/ml had a significant improvement in median survival when compared with patients with pan-cytokeratin +/CXCR4+ >2,500 cells/ml (not achieved versus 14 weeks). CXCR4 expression was found on NSCLC tumors and at sites of tumor metastasis.

CONCLUSION

This study suggests that CXCR4 may be a prognostic marker in NSCLC, and provides hypothesis-generating results, which may be important in determining metastatic potential. In future studies, we will prospectively evaluate the prognostic significance of pan-cytokeratin/CXCR4+ cells, and determine the mechanisms involved in the regulation of CXCR4 expression on tumor cells in a larger patient population.

Inhibition of chemokine receptor expression on uveal melanomas by CXCR4 siRNA and its effect on uveal melanoma liver metastases

PURPOSE

To determine whether blocking the expression of the chemokine receptor CXCR4 using siRNA inhibits chemotactic responses of human uveal melanoma cells to liver-derived factors and prevents liver metastases.

METHODS

Human uveal melanoma cells were transfected with CXCR4 siRNA or control siRNA and tested in vitro for chemotactic and invasive behavior in response to soluble factors produced by human liver cells. The effect of CXCR4 siRNA transfection on the formation of liver metastases was tested by injecting transfected melanoma cells into the spleen capsules of NOD-SCID mice, and metastases were quantified by measuring the human housekeeping gene hHPRT in livers.

RESULTS

Blocking CXCR4 interaction with its ligand using anti-CXCL12 antibody resulted in a significant reduction in the chemotactic responses of uveal melanoma cells to soluble factors produced by human liver cells. Similarly, blocking CXCR4 gene expression by transfection with CXCR4 siRNA inhibited both the chemotactic and the invasive properties of uveal melanoma cells exposed to factors produced by human livers. Uveal melanoma cells transfected with CXCR4 siRNA produced fewer liver metastases than untreated uveal melanoma cells or uveal melanoma cells transfected with control siRNA.

CONCLUSIONS

CXCR4 is a key chemokine receptor that may account for the organ-specific homing of human uveal melanomas to the liver, which contains significant quantities of CXCL2, the only known ligand for CXCR4. CXCR4 is a potential therapeutic target for preventing the initial establishment of liver metastases but has limited application for use in advanced liver tumors.

Effect of pro-inflammatory cytokine stimulation on human breast cancer: implications of chemokine receptor expression in cancer metastasis

Interactions between tumour cells and microenvironments may affect their growth and metastasis formation. In search for a better understanding of the role of cellular mediators in the progression of cancer, we investigated the effect of pro-inflammatory cytokines IL-1, IL-6, TNF-alpha and IFN-gamma on the regulation of expression of chemokine receptors CXCR4, CXCR2, CX3CR1, CCR9, and CCR5 in the human breast cancer cell line MCF-7. Our results showed that IL-1 increased CXCR4 expression whereas TNF-alpha increased CX3CR1, CCR9 and CCR5. Interestingly, this regulation was not homogeneous, emphasizing the inherent heterogeneity in cancer that may be responsive to specific inflammatory microenvironments.